The Tiruvallur police seized five lorries used to smuggle sand from Poondi and Aarani rivers on Saturday.
The police have filed cases against the owners of trucks for taking the river sand without permission.
Police said complaints were received about unauthorised excavation of sand from the two rivers. Based on the complaints, police teams were involved in surprise inspections in the two police limits where five trucks were engaged in smuggling sand. The patrol teams seized the vehicles.
The Tiruvallur Police have arrested 12 persons including the owners of the trucks for smuggling sand from river beds without permission and causing loss to the exchequer.
